12th International Symposium on District Heating and Cooling

Z Y networkx1 D ADx1X = value network in new state (€)Y = current network value (€)Rx LZ = required annual maintenance costs (€)x = pipex(4)Rx = construction costs per meter pipe dimension x (€)Lx = length of pipe x (m)D = lifetime expectancy (year)Ax = age of pipe x (year)The network degradation is defined as factor :YX (5)From consultation with amongst others COWI, it wasconcluded that networks with a < 0.5 are in a criticalstage.For the entire grid the was above the threshold.Discriminating the for separate grid sections helpedto identify the hotspots and monitoring will help todetermine the effect of SlimNet.Sustainability assessment modelTo assess the current sustainability results of thenetwork, SVP developed a sustainability assessmentmodel in accordance with Dutch law and guidelines,resulting in Fig. 3 [5]. This model can also predict theeffects of optimization in the chain from production,distribution and delivery to customer installationsThe <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaStrategic meteringIt was concluded that actual data on heat loss onsmaller scale (houses and clusters of houses) wouldfacilitate decision making on future renovation projectsand grid management. To get hold of this informationSVP installed heat meters with radio transmissionmodules on strategic positions in the network. Togetherwith the metering data from heat meters in customerinstallations this firstly gives accurate data on the heatloss in the corresponding part of the grid. This setupwill also provide us with empirical data on the long termresults of network improvement measures.In order to make the data comparable, two areas wherechosen. One with the new SlimNet approach (Usingpolybutene pipes and new construction techniques)and one with conventional material and constructiontechniques. First comparative results will be availableby the end of 2010.Leak detectionMost producers of pre-insulated pipe systems offer thepossibility of leak detection wiring. Using a master planwith proper zero and recurrent measurements thiswould be a reliable method of leak detection.Unfortunately this is not applicable to the situation inPurmerend.With one of its partners SVP developed a method usingtracer gas to detect leakages. The detection devicesproofed to be very sensitive and with this methodalmost 2.500 houses have been inspected this yearand last year. Leakages were detected in 3% of thosecases, mostly in an early stage, that otherwise wouldonly have been detected through visual sighting ofdamp.DEVELOPING AND DEFINING MEASURESIt became clear soon that the only way to improvenetwork performance was to rigorously renovate thehotspots and to start implementing a structuralmaintenance program in accordance to Z, Eq. 4.In sum the challenge was: a.) cost effectively renewingthe steel pipes with wet insulation in narrow crawlspaces while b.) improving network efficiency.Fig. 3 CO 2 reduction DH-network Purmerend in pastIt appeared that the ratio of CHP operation to the totalof heat produced and the heat loss factor have thebiggest impact on the sustainability results.To meet (a), SVP started the first two pilots in 2008with pre-insulated steel flex piping material, using twodifferent construction methods. Both pilots met thetechnical requirements but were too time consuming,costly and, because access to the crawl spaces had tobe gained by digging in the gardens, meant hugeinconvenience for customers.Parallel to this SVP had challenged pipe manufacturesto come up with innovative material constructionmethods, suitable for the Dutch situation (groundwater56